Baghdad , Iraq -LRB- CNN -RRB- Iraqi forces appeared Wednesday to be making progress on the third day of a major offensive intended to push ISIS fighters out of the city of Tikrit .

The Iraqi soldiers are reportedly approaching the city from five directions , as they seek to prevent ISIS militants from either escaping from Tikrit or sending in reinforcements to bolster its defense .

The operation is part of a wide-scale offensive to retake Tikrit and Salahuddin province ordered by Iraqi Prime Minister Haider al-Abadi on Sunday .

It has highlighted the role played by neighboring Iran in the fight against ISIS , at a time when the United States and five other world powers are negotiating with Tehran on a controversial deal to curb its nuclear program .

The semiofficial Iranian FARS news agency reports that Qassim Sulaimani , the commander of the elite Iranian Al-Quds Brigade , is helping oversee the operation to retake Tikrit .

Iran has provided advisers , weapons and ammunition to the Iraqi government . According to the Pentagon , there may be Iranians operating heavy artillery and rocket launchers as well .

Despite the reported Iranian assistance , the Iraqi forces face no easy task as they seek to advance on Tikrit .

Besides the direct threat posed by ISIS fighters , they must also avoid the large numbers of homemade bombs that litter the approaches to the city .

Iraq has not asked the U.S.-led coalition against ISIS to provide air cover for the operation to retake Tikrit .

ISIS released a number of propaganda images Wednesday , showing several vehicles and dozens of ISIS militants with their weapons , which it said were part of a military reinforcement of Salahuddin province .

CNN can not independently confirm the authenticity of the photographs .

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Why battle for Tikrit will defeat ISIS

Tikrit fell to ISIS in June of 2014 , after the group 's capture of Iraq 's second-largest city , Mosul . Tikrit is best known to Westerners as the birthplace of former Iraqi dictator Saddam Hussein .

ISIS , the radical Sunni militant group , has been on a murderous campaign to establish a caliphate across swaths of Iraq and Syria .

On Monday , Iraqi forces approached Tikrit from several fronts , Iraqiya TV reported , engaging with ISIS north of the city at al-Alam and south of the city at al-Dour .

The element of surprise probably was not a factor , as reports of Iraqi troops amassing near Tikrit were widely shared .

What awaits the Iraqi army is most likely a long , hard slog and not a quick rout . Tikrit is a big city , and the army and its associated militias have had problems recapturing much smaller towns from ISIS .

There have been several failed attempts to recapture Tikrit since the second half of 2014 . While Iraqi forces have gained some territory in the area , it has generally been under ISIS control for the last eight months or so .

Prime Minister al-Abadi , who is also commander in chief of the armed forces , said on Twitter that he would `` oversee the operation to liberate Tikrit '' from ISIS .

The joint Iraqi forces fighting to retake Tikrit include Iraqi troops , members of the Shia al-Hashed al-Shaabi militia , members of the Sunni Sons of Salahuddin brigades and other Sunni tribal fighters .

The offensive involves around 30,000 fighters in all .

Rights group Human Rights Watch on Wednesday urged government forces to protect civilians from revenge attacks by pro-government militias as they fight to retake Tikrit .

The rights group said it had documented `` numerous atrocities against Sunni civilians by pro-government militias and security forces '' after they recaptured other towns .

Human Rights Watch also warned that ISIS could seek to use civilians as human shields .

`` All commanders in Tikrit need to make sure that their forces protect civilians and allow them to flee the combat zone , '' said Joe Stork , the group 's deputy Middle East and North Africa director .

`` Past fighting raises grave concerns that Tikrit 's civilians are at serious risk from both ISIS and government forces , and both sides need to protect civilians from more sectarian slaughter . ''

CNN 's Ben Wedeman reported from Baghdad and Laura Smith-Spark wrote in London . CNN 's Mariano Castillo and Mohammed Tawfeeq contributed to this report .

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Iraqi forces make some progress as they seek to advance toward Tikrit

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The city , best known to Westerners as Saddam Hussein 's birthplace , was taken by ISIS in June